truba

1. trumpet
   Moj brat svira trubu u orkestru. — My brother plays the trumpet in an orchestra.
   U Guči se truba čuje po celu noć. — In Guča you can hear trumpets all night long.
2. colloq. (in a car) horn
   Vozač je pritisnuo trubu na raskrsnici. — The driver honked the horn at the intersection.
3. slang (of a person or thing) a hopeless case; a dud; rubbish
   On je truba za matematiku. — He's hopeless at maths.
   Taj film je prava truba. — That film is total rubbish.
4. (of fabric) bolt of cloth
   Kupili su celu trubu platna. — They bought a whole bolt of cloth.

To play the trumpet is svirati trubu (accusative, no preposition).